Magnetic disc drive systems frequently use the contact start stop (CSS) system. In the CSS system, a recording reproducing head slider contacts with the surface of a magnetic storage disc in the stand-by condition where the disc is stopped, and an air gap is formed between the head slider and the surface of the disc, upon rotation of the disc at a present speed, to disengage the head slider from the disc during the recording or reproducing operation. During operation, the disc and the head slider may be abraded or wear at the time the head slider moves away from the surface of the disc, or the head slider accidently contacts the surface of the rotating disc during the recording or reproducing operation, instead of being maintained in a position floating above the surface of the disc. Contact during rotation of the disc can lead to scratching or other damage of the disc and the head slider.
Some protection of the magnetic recording layer is obtained by an overcoat, where various materials have been reported for use as overcoats. For example, U.S. Pat. No. 4,069,360 uses an amorphous inorganic oxide layer formed on the thin film of a magnetic metal medium and a silicon containing lubricant layer coated over the amorphous inorganic oxide layer. A silicon based oil or silicon type surface coupling agent serves as the lubricant which adheres to the inorganic outside layer. U.S. Pat. No. 4,152,487 employs a non-magnetic alloy disc substrate, a thin film of a magnetic metal medium applied on the substrate and a polysilicate layer to cover the magnetic metal medium. Further lubrication may be obtained using fluorinated polyethers. U.S. Pat. No. 4,268,556 employs fluorinated polymers having a low molecular weight and containing a functional group at the termini as a lubricant for magnetic recording discs. U.S. Pat. No. 4,529,659 uses a lubricant comprising a fluorinated hydrocarbon polymer having a terminal carboxyl group which forms a salt with an aminosilane layer chemically coupled to a silicon oxide layer applied on the magnetic storage medium of a disc. U.S. Pat. No. 5,227,211 employs a perfluoropolyether lubricant for coating onto a carbon overcoat.